1. Field of the Invention:
This invention relates to a method and apparatus for making an annular member of precise tolerances such as can be used in the manufacture of a wheel for a heavy truck.
2. Description of the Prior Art:
One present procedure for making wheels for large trucks involves the casting of the wheels out of steel. The wheels when made in this way are relatively heavy and expensive. It is desirable that an improved procedure for making such wheels be provided, which procedure is less expensive and requires less metal and thus less weight than such casting. One procedure for making barrels which has been used in the production of commercially-used barrels for approximately a year and a half involves the use of fluid as the expanding medium. The workpiece blank is dropped over a post having a pair of spaced annular liquid seals mounted in annular grooves on the post. The seals are expanded radially outwardly by reducing the axial dimension of the annular grooves in which the seals are mounted causing the seals to firmly engage the workpiece blank thereby defining a sealed space bounded by the post, the two annular seals and the workpiece blank.
The workpiece is then expanded by pumping oil under pressure into the space through the post. A radially segmented outer die is used to form the outside configuration of the barrel, the pressurized oil acting to force the workpiece against the radially segmented outer dies. Such barrel making apparatus and procedures are not satisfactory for making heavy truck wheels because the great pressures needed to expand the heavy gauge metal necessary for the wheels has a tendency to radially displace the radially segmented dies used in the barrel manufacture. Furthermore, such radially segmented dies produce segment marks on the workpiece during the expanding process. Also, the substantial pressure necessary to expand the workpiece has a tendency to extrude the annular seals between the post and the outer dies.
The prior art may involve the following U.S. Pat. Nos.: 2,435,306; 2,955,556; 3,102,502; 3,298,218; 3,335,590; 3,391,559; 3,585,828; 3,729,795 and 3,834,212. The patent to Early discloses a procedure for simultaneous expansion and columnar deformation of a workpiece; however, the combining of such procedures is difficult to control as evidenced by the fact that the Early patent is proposing a solution to the problems involved in such control.